Hydrolutos breweri sp. n., a new aquatic Lutosini species (Orthoptera: Anostostomatidae) from Churí-tepui (Chimantá Massif, Venezuela)

2010·3.8 MB·English

by  Tomáš Derka

Zootaxa 2653: 51–59 (2010) ISSN 1175-5326 (print edition)
www.mapress.com/zootaxa/ Article ZOOTAXA
Copyright © 2010 · Magnolia Press ISSN1175-5334(online edition)
Hydrolutos breweri sp. n., a new aquatic Lutosini species (Orthoptera:
Anostostomatidae) from Churí-tepui (Chimantá Massif, Venezuela)
TOMÁŠ DERKA1 & PETER FEDOR2, 3
1Department of Ecology, Faculty of Natural Sciences, Comenius University, Mlynská dolina, 84215 Bratislava, Slovakia
2Department of Ecosozology, Faculty of Natural Sciences, Comenius University, Mlynská dolina, 84215 Bratislava, Slovakia
3Corresponding author. E-mail: [email protected]
Abstract
Hydrolutos breweri, anew species of Lutosini (Orthoptera: Anostostomatidae) from Cueva Charles Brewer (Churí-tepui,
Guyana Highlands, Venezuela) is described and figured. Inhabiting aquatic environment it represents an unusual
orthopteran with sternal and pleural area covered by fine microtrichia forming aplastron.
Key words: Orthoptera, Anostostomatidae, Hydrolutos, aquatic, Venezuela, tepui
Introduction
As atypical almost wholly southern hemispheric group of orthopterans Anostostomatidae are believed to owe
their distribution to the split of Gondwana (Fleming 1979; Gibbs 2006), however, adispersal factor to some
islands should be taken into account (Knapp et al. 2005; Pratt et al. 2008). The whole family, formerly
included in Stenopelmatidae, has been connected with plenty of longstanding nomenclatural problems, but
some of them have been resolved through examination of most of the types (Johns 1997; Gorochov 2001; Jost
and Shaw 2006). In their analyses Pratt et al. (2008) found support for the monophyly of Anostostomatidae
and for the close relationship with the Gryllacrididae and Stenopelmatidae. Anostostomatids occupy avariety
of ecological conditions across their zoogeographical range. Their unique phylogenetic status supports
achallenge for specific conservation (Gibbs 1998; Johns 2001).
The South American Hydrolutos species are medium-sized flightless anostostomatids. The genus
Hydrolutos (Orthoptera: Anostostomatidae) was known by 4 species: H. auyan Issa and Iaffe 1999, H.
chimantea Issa and Iaffe 1999, H. roraimae Issa and Iaffe 1999, H. aracamuni Issa and Iaffe 1999, described
from four different table mountains – tepuis in SE Venezuela (Issa and Iaffe 1999). Tepuis are peculiar flat-
topped table mountains, typical for the Guyana region. They are separated from surrounding wide lowlands
and uplands by the sheer cliffs. Tepuis are composed of quartzites and sandstones of the Precambrian Roraima
Group, overlaying the igneous metamorphic Guyana Shield (Gibbs and Barron 1993). The Guyana Shield
occupies the area of north-eastern South America, extending between the Orinoco River to the north and the
Amazon River to the south (Fig. 1A). The Guyana region is known for its extraordinary diversity and high
level of endemism, which is, above all, remarkable at the tops of the isolated table mountains (Huber 2005;
Rull 2005; Rull and Nogué 2007). The ecological community of their summits is considered a distinct and
discontinuous biogeographical province called Pantepui. Pantepui ranges from 1,500 to 3,000 m a.s.l. and
covers an area of about 5,000 km2(Berry et al. 1995, Huber 1995). Tepuis are acknowledged islands
supporting high endemism (Huber 2005; Rull 2007; Breure 2009; Breure and SČchlögl 2010). This includes
many aquatic species with a limited (endemic) geographical distribution (e.g. iampor and Kodada 1999;
Kodada and Jäch 1999; Derka 2002; Derka et al. 2009), such as those of Hydrolutos (Issa and Iaffe 1999). All
Accepted by D. Rentz: 22 Sep. 2010; published: 21 Oct. 2010 51
of them appear as unique and unusual in their aquatic ecology, enabled by a plastron-like structure on pleuro-
sternal area of thorax and abdomen. Occurrence of numerous specimens of some giant orthopterans from the
genus Hydrolutos from 10 to 12 cm of length that submerged underneath the water in case of danger was
reported by Charles Brewer-Carías from a newly discovered gigantic cave Cueva Charles Brewer at Churí-
tepui (Fig. 1C) in Chimantá massif (Šmída et al. 2005). The Chimantá massif (approx. 05°15' N 062°10' W) is
a series of tepuis in the eastern part of the Guyana Highlands (Fig. 1B). Recently an international scientific
expedition has explored the cave systems at Churí-tepui (Šmída et al. 2010). This paper reports on the new
Hydrolutos species from the cave Cueva Charles Brewer at Churí-tepui. Moreover, male genitalia of the genus
Hydrolutos arefigured for the first time.
FIGURE 1. The region of Churí-tepui (Chimantá Massif, Venezuela). A. Venezuelan Guayana (white rectangle) with its
Chimantá massif. B.Map of Chimantá massif with location of tepuis (modified after Huber 1995). C.Churí-tepui.
52 · Zootaxa 2653 © 2010 Magnolia Press DERKA & FEDOR
Material and methods
Material was collected inside the cave Cueva Charles Brewer at Churí-tepui at the Chimantá Massif,
Venezuela (Fig. 1), manually or using a hydrobiological kick-net and stored in pure ethanol. Morphological
characters were studied and photographed using stereomicroscope Leica M80. The holotype has been
preserved dry and pinned. The paratypes are stored in 70% ethanol.
Systematic considerations and taxonomy. Issa and Iaffe (1999), describing the genus, gave the basic
information on morphology of four species to distinguish them from other Lutosini relatives. However, the
original description is short, with no sufficient details and many points may be applied to some other genera.
Moreover it contains several disputable statements and figures.
The original paper by Issa and Iaffe (1999) declares front and middle coxae with no spines, but on the
contrary forecoxa carries a moderate lateral spine and midcoxa a short blunt spine. Information on middle
tibiae ventrally with a raw of 4 spines on internal side and a line of 3 spines on external side may be most
probably expressed as lapsus calami as the spines are situated dorsally. Male genitalia were not figured and
described. Therefore the taxonomic status of Hydrolutos should be discussed and revised more in detail.
Family Anostostomatidae Saussure 1859
Sub-Family Lutosinae Gorochov 1988
GenusHydrolutos Issa & Iaffe 1999
External morphology is highly conserved in this genus, for all species as in the original description of
Hydrolutos by Issa and Iaffe (1999). In body length the species range between 54–38 mm in males and 62–38
mm in females, that tend to be slightly larger than males.
Apterous, nocturnal, brown-coloured anostostomatids. As aquatic insects, on thorax and abdomen with
sternal and pleural area covered by fine microtrichia forming a plastron. Head width usually the same than
pronotum width. Fastigium horizontal, slightly flattened, not declinate with a definite median carina. Vertex
convex. Maxillary palps well-developed, 5 segmented, S1 and S2 short, S3-S5 longer. S5 terminally pilous
and swollen. Eyes weakly elevated, oval and pigmented.
Pronotum slightly elevated over mesonotum, as long as broad, with lateral margins indistinct. Thoracic
sterna with 2 spines, on prosternum blunt, on mesosternum and metasternum longer, erected. Front tibiae with
tympanal organs present on both sides, dorsally with 1 or 2 spines subapically and 2 apically, ventrally with
2 rows of 5 spines (including the apical ones). Middle tibiae dorsally with a row of 4 spines on internal side
and a row of 3 spines on external side, ventrally with 2 rows of 5 spines. Hind tibiae with 2 lateral combs,
ventrally with 2 long subterminal and 2 long terminal spines. Front femora without spines, but wrinkled on
inner margins. Hind femora laterally compressed and with 2 combs of short spines on inner margins.
Abdomen towards S9 uniformly segmented. In males epiproct convex, bilobulate apically, with long cerci.
Subgenital plate as long as broad. In females ovipositor medium-sized, curved upwards.
Diagnosis. The main difference is in sternal and pleural area covered by fine microtrichia forming
aplastron, generally unique within orthopterans. Pronotum gently projected over mesonotum, as long as
broad. In Apotetamenus Brunner von Wattenwyl pronotum caudally projected over mesonotum. Front coxae
with adistinct spine, medium coxae with blunt spine and hind coxae without aspine. Subgenital plate carries
short styles, but there are longer in Lutosa Walker.The species of Neolutosa Gorochov have a typical structure
of male abdominal apex, including complicated processes of paraprocts.
Hydrolutos breweri Derka & Fedor sp. nov.
Description. Male.
A NEW AQUATIC HYDROLUTOS SPECIES Zootaxa 2653 © 2010 Magnolia Press · 53
Colour and markings: Body dark brown. Head capsule, including mandibles, dark brown with a bright
belt-like pattern on vertex and 3 bright spots triangularly situated on frons, shiny and almost smooth, eyes
black. Palpi light basally and distally, with dark middle section. Thorax and abdomen very dark brown
dorsally, with light bands on terga (light area on pronotum). Legs brighter than body (Fig. 2, 3).
FIGURE 2. male Hydrolutos brewerisp. n. —a total view.
FIGURE 3. male Hydrolutos brewerisp. n. —a total view.
Head: Antennal flagellum about 2.5 times total body length, proximally smooth, in middle and distal
section swollen and covered by short fine microsetae. Fastigium as broad as antennal segment S1, horizontal,
slightly flattened, not declinate, with a median carina. Vertex convex, clypeus subtriangular with indistinct
median carina. Labrum heart-shaped, proximally broader than distally, with median carina in its apical half.
Maxillary palps bright, the last segment swollen and covered by short fine and soft microsetae. Eyes elevated
in frontal view (Fig. 4).
Thorax: Pronotum slightly elevated over mesonotum, as long as wide, bordered by a smooth rolled
margin, containing both smooth and gently rugose areas. All thoracic sterna with 2 spines, prosternum: 2
moderate spines posterolaterally elevated, mesosternum: 2 spines posterolaterally elevated, metasternum: 2
distinct spines with no lateral elevation (Fig. 2, 3).
Legs long, forecoxa with a moderate lateral spine, midcoxa with a short blunt spine, femora without
spines. Fore tibiae dorsally with 2 spines subapically and 2 apically, ventrally with 2 rows of 5 spines
(including the apical ones). Middle tibiae dorsally with a row of 4 spines on internal side and a row of 3 spines
on external side, ventrally with 2 rows of 5 spines. Hind tibiae with 2 lateral combs of short but firm spines,
ventrally with 2 moderate subterminal and 2 superior terminal spines. Tympanum elypsoid, dark brown.
Abdomen: Abdominal apex and genitalia as on Figures 5, 6, 7. Abdominal tergites smooth with fine
transverse striae mesally and with posterior edges darker. Genitalia pubescent. Supra-anal plate bilobulate
terminally slightly curved upwards. Cerci cylindrical, rugose, directed gently upwards, with blunt apices and
without internal processes. Subgenital plate as long as wide, very gently concave laterally, without any
emargination between styles, with flat posterior margin and long styli directed ventrad.
Measurements. Body length 43.2 mm (including cerci 47.1), fastigium width 1.2 mm, interocular space 5
mm, pronotum length 9.9 mm, width 11.1 mm, hind femur length 35.5, width (7 mm max.), (2 mm min.), hind
tibia length 35.5 mm, hind tarsus length 11.3 mm, hind tarsi length: I 4.1 mm, II 3.0 mm, III 2.1 mm, IV 1.5
mm, abdomen length (without cerci) 22.4 mm.
Female. Unknown.
54 · Zootaxa 2653 © 2010 Magnolia Press DERKA & FEDOR
FIGURE 4. Head of male Hydrolutos brewerisp. n.—a frontal view (photographed by C. Brewer-Carías).
A NEW AQUATIC HYDROLUTOS SPECIES Zootaxa 2653 © 2010 Magnolia Press · 55
FIGURE 5. Genitalia of male Hydrolutos brewerisp. n. —a dorsal view.
FIGURE 6. Genitalia of male Hydrolutos brewerisp. n. —a lateral view.
56 · Zootaxa 2653 © 2010 Magnolia Press DERKA & FEDOR
FIGURE 7. Genitalia of male Hydrolutos brewerisp. n. —a ventral view.
FIGURE 8. MaleHydrolutos brewerisp. n. in its natural habitat.
%
Material examined. Holotype. 1 body length 43.2 mm, Venezuela, Edo. Bolívar, Chimantá Massif,
Churí tepui, Cueva Charles Brewer, ca 2300 m a.s.l., 15.I. 2009. Holotype has been preserved dry and pinned.
% &
Paratypes. body length 43 mm, 1 nymph, body length 30 mm. The same data as holotype. The
paratypes are stored in 70% ethanol. Holotype and paratypes will be deposited in Museo del Instituto de
Zoología Agrícola (MIZA), Facultad de Agronomía, Universidad Central de Venezuela, Maracay, Edo.
Aragua, Venezuela.
A NEW AQUATIC HYDROLUTOS SPECIES Zootaxa 2653 © 2010 Magnolia Press · 57
Etymology. Species named in honour of Charles Brewer-Carías, in recognition of his great contribution to
exploration of Venezuelan Guyana. He has led over 200 expeditions in Venezuelan Guyana Highlands. His
most famous discoveries are in geological features in the tepuis such as the giant sink holes on Sarisariñama,
the world’s largest quartzite cave on Churí-tepui and many other previously unexplored caves.
Ecology. As other members of the genus, H. breweri inhabits aquatic habitats. Numerous individuals
were observed walking and swimming inside the stream and walking outside the water at the bottom and
walls of the Cueva Charles Brewer (Fig. 8). Thanks to high ability to cling by means of strong legs and tarsal
claws it is able to move even against strong current. Because of permanent darkness in the cave, individuals
were observed active 24 hours, not only during the night as it was reported for other members of the genus
(Issa & Iaffe 1999, pers. observ.). However, it can not be considered troglobiont because of lack of typical
adaptations (e.g. reduction of eyes and coloration), and the occurrence of this species can be expected in other
streams at Churí-tepui plateau outside the Cueva Charles Brewer.
Diagnosis. The species is easily distinguished on afew characters. Clypeus triangular (subtriangular in H.
chimantea), laterally more distinct than in H. ayuan. Palpi bright but dark in H. aracamuni. Labrum heart-
shaped, but oval in H. raraimae and H. auyan. Fastigium as broad as antennal segment I, but broader in H.
roraimae and H. aracamuni. Epiproct bilobulate terminally, but oval in H. aracamuni. H. breweri is unique
among other members of the genus by extremely long hind tibiae reaching length of hind femur. In remnant
Hydrolutos species hind femur is always longer then hind tibia.
Acknowledgements
We would like to thank the members of the Venezuelan-Slovakian speleological expedition, notably its main
organizers Charles Brewer-Carias and Branislav Šmída. We are acknowledged to Michal Poljak and Dr. Ján
Kodada (both from Comenius University, Bratislava, Slovakia) for the help with taking and processing
pictures of the type material. We also thank to Dr. Martin Mrva from Department of Zoology, Faculty of
Sciences, Comenius University, Bratislava, Slovakia who figured the holotype (Fig.2). Research was
supported by grants APVV 0251-07, VEGA 1/0246/08, VEGA 1/0155/08 and KEGA 3/7454/09.
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